Go to Walmart and purchase a couple Black Bed Sheets (Approx. $4.00 for a twin size). I purchased two of them and put grommets in them so I can hang them from hooks on the ceiling. They work very well and when not in use i fold them up to store them.

Hey KJ - I just bought a few pieces of black cardboard from an art supply store. I clamp them to a light stand or to the side of a light and they work great. Mine are 11x14 and 20x30 but almost any size will work.